Two-dimensional sound-localization behavior of early-blind humans

To investigate whether the visual system is crucial for adequate calibration of acoustic localization cues, sound-localization performance of early blind humans was compared with that of sighted controls. Because a potential benefit of vision is mainly expected for targets within the two-dimensional (2D) frontal hemifield, localization was tested within this target range, while using sounds of various durations and spectral content. Subjects were instructed to point, in separate experimental sessions, either with their left arm, or with their nose, in the direction of the perceived target position as accurately as possible. The experiments required the use of all available sound-localization cues such as interaural differences in phase and intensity, as well as the complex spectral shape cues provided by the pinnae. In addition, for long-duration stimuli, subjects could have had access to head motion-induced acoustic feedback. Moreover, the two pointing methods allowed us to assess different response strategies for the two groups. In an additional series, subjects were instructed to respond as quickly as possible. The results show that, in general, 2D sound-localization performance of blind subjects was indistinguishable from that of sighted subjects, both for broad-band noise and for pure tones. In the fast head-pointing task, the latency distributions of both groups were equal. These findings suggest that visual feedback is not required to calibrate the available localization cues – including the idiosyncratic and complex spectral shape cues for elevation. Instead, the localization abilities of blind people show that the putative supervising role of vision may be supported, or taken over, by other non-visual feedback systems. The results do not provide support for the hypothesis that blind people can hypercompensate for the loss of vision in the frontal hemifield by developing superior sound-localization abilities. Despite the general correspondence in localization behavior, some specific differences related to pointing strategies as well as to those between blind and sighted subjects were apparent. Most importantly, the reconstructed origin (bias) of arm pointing was located near the shoulder for the blind subjects, whereas it was shifted and located near the cyclopean eye for the sighted subjects. The results indicate that both early blind and sighted humans adequately transform the head-centered acoustic target coordinates into the required reference frame of either motor system, but that the adopted response strategy may be specific to the subject group and pointer method. Electronic Publication     

Anatomical distribution of the growth-associated protein GAP-43/B-50 in the adult rat brain

GAP-43 (B-50,F1,pp46) is a neuron-specific phosphoprotein that has been implicated in the development and modulation of synaptic relationships. Although most neurons cease expressing high levels of GAP-43 after the completion of synaptogenesis (Jacobson et al., 1986), certain brain regions continue to have considerable amounts of the protein throughout life (Oestreicher et al., 1986); in at least one such area, the phosphorylation of the protein has been linked with the events that underlie synaptic potentiation (Lovinger et al., 1985). In this study, we used the indirect immunoperoxidase method to map the distribution of GAP-43/B-50 in the brains of 8 adult rats with 2 different antibodies: a monospecific, polyclonal antibody prepared in sheep against the purified protein and an affinity-purified IgG prepared in rabbits. Specific immunoreactivity was found primarily in the neuropil and followed a generally increasing caudal-to-rostral gradient along the neuraxis. Densest staining occurred in layer I of the cortex, the CA1 field of the hippocampus, and in a continuum of subcortical structures that included the caudate-putamen, olfactory tubercle, nucleus accumbens, bed nucleus of the stria terminalis, amygdala, and medial preoptic area-hypothalamus. In the brain stem, staining was seen in the central gray and in ascending visceral relay nuclei, but was essentially absent in areas related to ascending somatosensory information (e.g., the cochlear nuclei or vestibular complex) and motor control (e.g., nucleus ruber or the motor nuclei of the cranial nerves). Staining in dorsal thalamus was likewise modest in most somatosensory and somatomotor relay nuclei, but dark in certain other structures (e.g., mediodorsal nucleus, lateral complex). This distributional pattern raises the question of whether synapses in all areas containing high levels of GAP-43/B-50 are capable of undergoing functional plasticity, or whether the protein may function in some of these areas in some other capacity (e.g., general signal transduction).     

In vitro study of the antimicrobial effects of radiological contrast agents used in arthrography

Aspiration arthrography using an iodinated contrast medium is a useful tool for the investigation of septic or aseptic loosening of arthroplasties and of septic arthritis. Previously, the contrast media have been thought to cause false negative results in cultures when present in aspirated samples of synovial fluid, probably because free iodine is bactericidal, but reports have been inconclusive. We examined the influence of the older, high osmolar contrast agents and the low osmolar media used currently on the growth of ten different micro-organisms capable of causing deep infection around a prosthesis. Five media were tested, using a disc diffusion technique and a time-killing curve method in which high and low inocula of micro-organisms were incubated in undiluted media. The only bactericidal effects were found with low inocula of Escherichia coli and Pseudomonas aeruginosa in ioxithalamate, one of the older ionic media. The low and iso-osmolar iodinated contrast media used currently do not impede culture. Future study must assess other causes of false negative cultures of synovial fluid and new developments in enhancing microbial recovery from aspirated samples.     

Distribution of growth-associated protein, B-50 (GAP-43) in the mammalian enteric nervous system

The presence of the growth-associated protein, B-50 (also known as GAP-43) was investigated in the adult mammalian enteric nervous system. The small intestine of rat, ferret and human was examined by immunohistochemistry. Dense B-50-like immunoreactivity was localized in nerves throughout the wall of the rat, ferret and human small intestine, notably in the myenteric and submucous plexuses, where in the ferret ileum it co-localized with vasoactive intestinal polypeptide-immunoreactive fibre groups. Material with the biochemical and immunological characteristics of rat B-50 was extracted from the rat ileum. In-situ hybridization demonstrated that enteric neurons express B-50. These findings are consistent with a role for B-50 in the documented plasticity of the adult enteric nervous system.     

Dephosphorylation of B-50 in synaptic plasma membranes

Synaptic plasma membranes from rat brain cortex possess intrinsic ability to dephosphorylate the endogenous protein B-50. At low concentrations of [gamma-32P]ATP, B-50 phosphorylation in synaptic membranes is maximal at 30 seconds, followed by dephosphorylation for an additional 60 minutes. The dephosphorylation of 32P-labeled B-50 is not sensitive to the protease inhibitor leupeptin and not correlated with a loss of the B-50 content of synaptic membranes as measured with immunoblot analysis. Dephosphorylation of membrane-associated B-50 is stimulated to a small extent by Mg2+ but not by Ca2+. Heat-stable protein phosphatase inhibitors prevent dephosphorylation of 32P-labeled B-50. Dephosphorylation of B-50 in synaptic membranes is stimulated by ATP, ADP, or adenosine 5'-O-thiotriphosphate, but not by adenine, adenosine, other adenine or guanine nucleotides, nonhydrolyzable analogs of ATP or GTP, nor by adenosine 5'-O-(2-thiodiphosphate). B-50, phosphorylated by exogenous protein kinase C and purified to homogeneity, has been used as a substrate to follow the purification of B-50 phosphatase activity. B-50 phosphatase activity can be solubilized from synaptic membranes with 0.5% Triton X-100 and 75 mM KCl. Chromatography of the extract on DEAE-cellulose yields enhanced B-50 phosphatase activity.     

Simultaneous determination of BNP7787 and its metabolite mesna in plasma and tissue by micro-HPLC with a dual electrochemical detector

Sensitive, accurate, and precise assays are described to determine BNP7787 (disodium 2,2'-dithio-bis-ethane sulfonate) and its metabolite mesna (sodium 2-mercaptoethane sulfonate) simultaneously in plasma and tissue by micro-high-performance liquid chromatography (HPLC) with dual electrochemical detection. After separation of BNP7787 and mesna by micro-HPLC, the disulfide BNP7787 was reduced to mesna by a reactor cell with a glassy carbon working electrode (-1.6 V versus Hy-REF). At the second electrode, which consisted of a gold wall-jet electrode, the mesna generated from BNP7787 and the mesna already present in the samples were detected (+0.85 V versus Ag/AgCl). The lower limit of quantification (LLQ) of both compounds was 3 microM in plasma and 20 nmol/g in tissue. The dynamic range of the assay in plasma was 3-120 microM for mesna and 15-1200 microM for BNP7787. In tissue, the dynamic range was 20-2000 nmol/g for both compounds. The recovery of mesna from plasma and tissue ranged from 61.4 to 90.5% and 82.7 to 90.2%, respectively, and seemed to be concentration dependent. The recovery of BNP7787 from plasma and tissue was complete (i.e., 101.5 and 96.4%, respectively). The within- and between-day accuracy and precision for the plasma and tissue assay were within 14 and 7%, respectively. The utility of the assay was shown by determination of the stability of mesna and BNP7787 in a kidney sample of a rat and by analysis of plasma samples obtained from a patient receiving 18.4 g/m(2) BNP7787 as a 15-min intravenous infusion.     

A detailed analysis of expedited regulatory review time of marketing authorization applications for new anticancer drugs in the US and EU

The aim of this study was to assess the effect of expedited regulatory approval programs used by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA), type of product (small molecule or biotechnology‐derived product) and consulting scientific advisory committees on the regulatory review time of the marketing authorization applications (MAAs) for new anticancer drugs. A dataset composed of 76 new anticancer drugs was constructed. The date of submission of the MAAs in the United States and the European Union were comparable. The typical review time of MAAs was 136 days shorter in the United States (201 days [median]) than in the European Union (337 days [median]). The type of product did not have a high impact on the review time. The review time of the MAAs for drugs undergoing priority review in the United States or accelerated assessment in the European Union at the stage of review of MAA was generally shorter than that for drugs following the standard regulatory pathway. The regulatory pathway using at least one expedited regulatory program at the stages of drug development, review of MAA, and approval of drug in the United States (172 days [median]), and that at the stages of review of MAA and approval of drug in the European Union (183 days [median]) enabled the shortest review time of MAAs. Referral to advisory committee meeting increased the review time of MAAs for drugs undergoing one or more expedited regulatory approval programs in the United States and the European Union close to that for drugs undergoing the standard regulatory approval pathway.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

The US Food and Drug Administration (FDA) has more expedited regulatory approval programs than the European Medicines Agency (EMA), suggested to result in earlier availability of anticancer drugs in the United States compared to in the European Union.

• WHAT QUESTION DID THIS STUDY ADDRESS?

The effect of expedited regulatory approval programs, type of product, and consulting scientific advisory committees on the regulatory review time of the marketing authorization applications (MAAs) for new anticancer drugs in the United States and the European Union.

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

It was shown that the review of MAAs for new anticancer drugs was finalized typically 136 days later and expedited regulatory programs were less frequently employed in the European Union compared to in the United States. The regulatory pathways leading to shortest review time of MAAs for new anticancer drugs were identified.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

A field of improvement for the regulatory framework in the European Union to enable earlier drug availability was indicated. Insight for the industry into combinations of expedited regulatory approval programs advantageous to apply for was provided.     

CTLA4 Gene Polymorphisms in Dutch and Chinese Patients with Inflammatory Bowel Disease

Background: Inflammatory bowel diseases (IBDs) are characterized by chronic intestinal inflammation as a result of an exaggerated T-cell response. CTLA4, a receptor of activated T cells, has an inhibitory function in regulating T-cell activation. Since CTLA4 gene polymorphisms have been associated with several autoimmune diseases, the aim was to study these gene polymorphisms in patients with IBD in two different populations. Methods: The C-318T polymorphism in the promoter region and A+49G polymorphism in exon 1 of the CTLA4 gene were investigated by a PCR-SSP method. We studied 139 unrelated patients with ulcerative colitis (UC), 163 patients with Crohn disease (CD) and 174 healthy controls of Dutch Caucasian origin as well as 35 patients with UC and 62 healthy controls from the Chinese Han population. Results: No significant differences in the distribution of allele, genotype and haplotype frequencies were observed between C-318T and A+49G gene polymorphisms and IBD in Dutch Caucasians and UC in the Chinese Han population. Although the haplotypes of the C-318T and A+49G polymorphisms were distributed differently between Dutch Caucasian and Chinese Han populations, there were no differences in the subgroups of patients with CD classified according to age, localization and behaviour in the Vienna classification and in those with UC classified according to age at onset, disease extension and presence of colectomy in the Dutch patients. However, the CTLA4-318 genotype CC was more frequent in patients with CD over 40 years (93%) than in younger patients (74%) ( P = 0.045). Conclusion: C-318T and A+49G CTLA4 gene polymorphisms and their haplotypes are not associated in Dutch Caucasian patients with IBD and in Chinese patients with UC.